/Engine/Source/Editor/GraphEditor/Public/SGraphActionMenu.h
Called when tree item dragged
[FReply](API\Runtime\SlateCore\Input\FReply) OnItemDragDetected ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )